| With the rapid development of industry and agriculture, sewage is discharged into surface runoff, and the water quality of lakes and rivers is deteriorating, seriously restricting the development of human and society. Surface water is widely distributed and lack of concentration therefore, it can not be purified with most common wastewater treatment process. Research and development of ecological restoration process for surface water become an important issue.In this study, firstly the suitability and purification effects of several floating bed plants and artificial medium were compared, preferred plants and artificial medium were constructed complex ecological floating bed system with supplemented ceramisite and EM agents. Secondly, purification effect and laws of floating bed system were investigated for micro-polluted water under different operating conditions. Thirdly, purification ability and denitrification mechanism of different combinations and each part of the floating bed system were researched. Finally the effect of the floating bed system was examined via pilot experimentsLythrum salicaria Linn, Typha minima Funk and Iris pseudacorus are three kinds of cold-resistant plants which are more suitable for northern planting. Activated carbon fiber and ecological carbon fibers are two kinds of carbon fiber artificial medium. Comparison experiments of these three floating bed plants and two artificial medium showed that more suitable plants and artificial medium for micro-polluted water were purification lythrum and ecological carbon fibers.The results showed that when the air/water ratio was2:1, the hydraulic loading was higher than0.33m3/m2·d, floating bed system exhibited more obvious decline in the removal rate of pollutants, and when hydraulic loading was less than0.33m3/m2·d, floating bed system had better treatment effect. When HRT was1d and gas-water ratio wass4:1, and the influent concentrations of COD, NH4+-N, TP and TN were35.66g/m2·d,6.86g/m2· d,0.54g/m·d and8.25g/m·d respectively, floating bed system had a good treatment effect, with the corresponding removal rates88.55%,97.76%,50.62%and40.96%, respectively.Different gas-water ratio experiments showed that the optimal gas water ratio of the system was4:1.With the air/water ratio of4:1, syestem had best removal efficiency of COD, NH4+-N, TP and TN, and the corresponding removal rates were88.55%,92.55%,68.71%and38.10%, respectively. With the air/water ratio of4:1, The removal efficiency of COD, NH4+-N, TP and TN of system was better under the conditions of continuous aeration than that of the intermittent aeration. In addition, the system removal rates of COD, NH4+-N, TP and TN in summer were9.76%,33.35%,23.01%and11.06%higher than that in winter respectively.Different combination of floating bed and different part of the decontamination ability of the research showed that, COD, NH4+-N, and TP removal rates of split-floating bed were12.95%,36.51%,8.88%and10.71%higher than one type of floating bed respectively; COD, NH4+-N and TP removal rates of plant-ceramsite part of the floating bed system were11.7%,23.15%and5.36%higher than artificial medium part. TN removal rate of artificial medium was7.63%higher than plant-ceramsite part. The denitrification process blocked in both of two parst, and NO3-N accumulated in the water.pilot experiment result of floating bed showed that during the stable operation, NH4+-N removal rate of floating bed system kept above than80%, and NH4+-N concentration of the effluent water was5mg/L or less, which can achieve NH4+-N level A requirements about discharge standard of pollutants for municipal wastewater treatment plant(GB18918-2002). In addition, the number of algae in water decreased obviously, and the system played a important role in controling algal. |
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